Halocarbon hydrogenolysis

ABSTRACT

Halocarbons such as CCl 2  F 2 , CF 3  CFHCl or CF 3  CFCl 2  which contain chlorine and/or bromine are contacted with hydrogen in the presence of silicon carbide and/or a metal selected from aluminum, molybdenum, titanium, nickel, iron or cobalt (or their alloys) at temperatures of 350° to 700° C. and pressures of 0 to 1000 psig to obtain a product wherein at least one chlorine or bromine in the starting material has been replaced by hydrogen.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.08/122,102 filed Sep. 16, 1993 now U.S. Pat. No. 5,364,992, which is acontinuation of U.S. patent application Ser. No. 07/847,987 filed Apr.9, 1992, now abandoned, a national filing of PCT application No.PCT/US90/05637 filed Oct. 9, 1990, which is a continuation-in-part ofU.S. patent application Ser. No. 07/418,832 filed Oct. 10, 1989, nowabandoned.

BACKGROUND OF THE INVENTION

This invention relates to a process for the hydrogenolysis ofhalocarbons.

At this time there is a desire to produce halocarbons of reducedchlorine content. Hydrogenolysis is a known method for doing this. Forexample, see U.K. Patent 1,578,933 which discloses a process for thehydrogenolysis of CF₃ CFHCl to CF₃ CH₂ F using a hydrogenation catalyst,e.g., palladium supported on alumina or carbon. Hydrogenolysis offluorochlorocarbons by passage through empty tubes made of variousmaterials is also known, e.g., U.S. Pat. No. 2,615,926 disclosesplatinum tubes, U.S. Pat. No. 2,704,775 discloses nickel or stainlesssteel tubes and U.S. Pat. No. 3,042,727 discloses a Vycor® tube.

It is desired to provide a process for converting a halocarbon to a morehydrogenated form with high selectivity and particularly to provide sucha process wherein formation of solids and plugging of reaction vesselsis minimized.

SUMMARY OF THE INVENTION

We have discovered an improved hydrogenolysis process for reducing thechlorine and/or bromine content of halocarbons. The process may be usedfor producing saturated halocarbon products such that the yield loss toolefins, coupled by-products, hydrocarbons or fragmented products isless than 10%. The process involves contacting a halocarbon of theformula:

    C.sub.n H.sub.m F.sub.p X.sub.q

wherein

X is Cl or Br,

n is 1 to 10,

m is 0 to 20,

p is 0 to 21,

q is 1 to 22,

provided that m+p+q equals 2n+2 when the compound is acyclic and equals2n when the compound is cyclic, and provided that when n is 1, q is atleast 2, with at least 0.1 mole of hydrogen per mole of halocarbon at atemperature of 350° to 700° C., and a pressure of 0 to 1000 psig, in areaction vessel (e.g., a tube) of aluminum, molybdenum, titanium,nickel, iron, cobalt, or their alloys, or of silicon carbide, optionallypacked with aluminum, molybdenum, titanium, nickel, iron, cobalt ortheir alloys, or an inert material (e.g., silicon carbide) for a timesufficient to produce a product wherein at least one of X has beenreplaced by a hydrogen atom. Preferred alloys consist essentially of oneor more metals selected from aluminum, molybdenum, titanium, nickel,iron and cobalt, optionally together with chromium and/or tungsten.

The process of the invention provides improved conversions andselectivity and has the further advantage that it does not produceolefins as the major product. Furthermore, the process minimizes theformation of solids fin the reaction vessel, thus permitting long-termoperation with less plugging.

DESCRIPTION OF THE INVENTION

An important aspect of the present invention is conducting thehydrogenolysis of halocarbons in the presence of silicon carbide and/orat least one metal selected-from aluminum, molybdenum, titanium, nickel,iron, cobalt or their alloys. The metals may be coated on the insidesurface of a reaction vessel (e.g., by plating or sputtering the metalsor their alloys onto the inside surface). Such coating can help tominimize corrosion of the reaction vessel well. A reaction vessel ofthese materials (e.g., a metal tube) optionally packed with the metal insuitable form or an inert material such as silica, silicon carbide orlow surface area carbon (e.g., shot coke) may also be used. Whenreference is made to alloys, it is meant a nickel alloy containing from1 to 99.9% (by weight) nickel, a cobalt alloy containing 1 to 99.9% (byweight) cobalt, an iron alloy containing 0.2 to 99.9% (by weight) iron,a molybdenum alloy containing 70 to 99.9% (by weight) molybdenum, analuminum alloy containing 80 to 99.9% (by weight) aluminum and atitanium alloy containing 72 to 99.8% (by weight) titanium. Preferablythe remainder of these alloys is selected such that the alloy consistsessentially of (i) one or more metals selected from aluminum,molybdenum, titanium, nickel, iron and cobalt, and optionally (ii)chromium and/or tungsten.

Most preferred for the practice of this invention are nickel or alloysof nickel such as those containing 52% to 80% nickel, e.g., Inconel® 600nickel alloy or Hastelloy® C276 alloy.

When used for packing, the metal, alloys or inert material may beparticles or formed shapes such as, for example, perforated plates,saddles, rings (e.g., Pall® rings), wire, screen, chips, pipe, shot,gauze and wool. Although an empty reaction vessel (e.g., an empty tube)may be used, the use of this type of packing material can provide theadvantage of minimizing backmixing. These types of packing material canalso serve as heat transfer materials. In many embodiments, perforatedplates, saddles and rings can be especially useful.

The invention is applicable to the hydrogenolysis of halocarbons. Thehalocarbons can contain 1 to 10 carbon atoms, preferably 1 to 4 carbonatoms, most preferably 1 to 3 carbon atoms. The halocarbons includecyclic as well as acyclic compounds and can be generically representedby the empirical formula C_(n) H_(m) F_(p) X_(q), where X is Cl and/orBr, preferably C1, and n is an integer from 1 to 10, m is an integerfrom 0 to 20, p is an integer from 0 to 21, and q is an integer from 1to 22, provided that m+p+q=2n+2 when the compound is acyclic and equals2n when the compound is cyclic. For single carbon compounds (i.e., nis 1) the invention is particularly applicable when q is at least 2.

In a preferred embodiment the halocarbons are represented by the aboveempirical formula where n=1 to 4, m is 0 to 8, p is 0 to 9, and q is 1to 9. Preferably, when n is 2 or more, p is at least 1.

The above halocarbons are either commercially available or can beprepared by known methods or adaptation of known methods.

As previously indicated these starting materials when subjected to theprocess of the invention will result in products wherein one or more X(e.g., chlorine)-has been replaced by hydrogen. Thus the products of thehydrogenolysis reactions of the C₁ halocarbons will contain one or twohydrogen atoms, preferably one, and those from C₂ compounds from one tothree hydrogen atoms, preferably one to two. The C₃ halocarbonshydrogenolysis products will contain one to five hydrogen atoms withthose containing one to four being preferred. In a similar manner the C₄to C₁₀ halocarbon products will contain one or more hydrogen atoms. Thepreferred process of this invention does not produce olefins as themajor product. Instead, the major product of the conversion is ahydrogenolysis product wherein at least one X of the halocarbon startingmaterial has been replaced by a hydrogen atom. This is particularlyimportant for the hydrogenolysis of halocarbons where n is 2 to 10(i.e., multicarbon halocarbons) where such factors as olefin productioncan be of concern at temperatures of 350° C. or more. For example, CF₃CCl₂ F can be converted with high selectivity to a hydrogenolysisproduct consisting primarily of CF₃ CHClF and CF₃ CH₂ F with very littleolefin formulation. In a preferred embodiment of this invention usinghalocarbons containing fluorine and chlorine, at least 90% of thehydrogenolysis products contain the same number of fluorines as theoriginal halocarbon. Furthermore the yield loss to olefins, coupledby-products, hydrocarbons, fragmentation products or carbon is less than10%.

Examples of olefins are products such as CClF═CCF₂ or CF₂ ═CF₂ theformer of which can be obtained from hydrogenolysis of CCl₂ FCClF₂ andthe latter from hydrogenolysis of CClF₂ CClF₂. An example of a coupledby-product is CF₃ CF═CFCF₃ which can be obtained by the hydrogenolysisof CClF₂ CClF₂. Examples of hydrocarbon products are CH₄, C₂ H₆ and C₃H₈ which can be obtained by the hydrogenolysis of CCl₂ F₂, CCl₂ FCClF₂and CF₃ CClFCF₃ respectively. Examples of fragmentation products are CF₃H and CH₂ F₂ which can be obtained by the hydrogenolysis of CF₃ CCl₂ Fand its isomer.

The reaction temperature can range from 350° C. to 700° C. Preferablythe reaction temperature is at least about 400° C.

The amount of hydrogen contained in the gas stream contacted with thegaseous halocarbon should be at least 0.1 mole per mole of halocarbon.Hydrogen amounts ranging from 0.2 to 5 moles per mole of halocarbon areused for some embodiments. In general, the amount of hydrogen preferablyranges from 0.2 to 60 moles per mole of halocarbon and more preferablyranges from 0.4 to 40 moles per mole of halocarbon. The hydrogen can befed either in the pure state or diluted with an inert gas, e.g.,nitrogen, helium, or argon.

The process pressure is operable over a broad range of pressures.Generally atmospheric (i.e., 0 psig) or superatmospheric pressures of upto 1000 psig are employed. Preferably the pressure is at least about 25psig.

The extent of the replacement of halogen by hydrogen increases withreaction time. Reaction times between 0.1 minutes and 25 minutes arepreferred. Most preferred are reaction times between 0.2 and 8 minutes.

An important feature of the process of the invention is that throughselection of the appropriate metal and process conditions, a desiredhalocarbon hydrogenolysis product can be obtained as the major productwith high selectivity and minimal formation of unwanted by-products.Preferably the reaction time and temperature are selected to obtain longterm. (>1000 hours) plug free operation and to provide as the majorproduct of the conversion hydrogenolysis product which retains thefluorine content of the starting halocarbon while at least one X isreplaced by hydrogen. In many embodiments the reaction time andtemperature are controlled so that at least about 90% of halocarbonconverted has the same number of fluorine atoms as the halocarbonstarting material. Also, in many embodiments the combined yield lossesto olefins, coupled by-products, hydrocarbons, or fragmentation productsis less than 10%.

An additional desirable feature is that through a selection of anappropriate reaction vessel and packing (e.g., metals, alloys, or inertmaterials) and process conditions, the products of the hydrogenolysiscan contain in high selectivity just one less chlorine or bromine thanwas present in the starting material. This is particularly useful when qis 2 or more, and it is desired to obtain a major product of theconversion, hydrogenolysis product which contains chlorine and/orbromine. For example, starting with a one-carbon compound containing twoor more chlorine or bromine atoms, products containing just one lesschlorine or bromine can be obtained in high selectivity.

Although substantial conversions can be achieved in a once-throughsystem, recycle of unreacted halocarbons or intermediates can beemployed in a conventional manner. The processes of this invention areconsidered to be characterized by relativity high activation energieswhen compared to catalytic hydrogenolysis over conventional Pd/Ccatalyst. For example, the activation energy for the hydrogenolysis ofCF₃ CCl₂ F over a 0.5% Pd/C catalyst at 167° C. to 200° C. was found tobe 14-17 Kcal/mole. The activation energy for the hydrogenolysis of CF₃CHClF over a 0.5%.Pd/C catalyst at 249° C. to 288° C. was found to be22-28 Kcal/mole. In contrast, the activation energies for thehydrogenolysis reactions of these compounds conducted in the reactionvessels of this invention, either empty or packed, were found to beconsiderably larger as exemplified in Table A.

                  TABLE A                                                         ______________________________________                                        Activation Energy Data                                                        High Temperature Hydrogenolysis                                                      Temp.                   Activation                                     Feed   Range     Packing       Energy                                         ______________________________________                                        F114.sub.a.sup.1                                                                     450-550° C.                                                                      --            49 ± 3 Kcal/mole                            F114.sub.x.sup.2                                                                     440-600° C.                                                                      --            47 ± 2                                      F124.sup.3                                                                           510-600° C.                                                                      --            49 ± 7                                      F114.sub.x                                                                           400-570° C.                                                                      shot coke     35 ± 1                                      F114.sub.x                                                                           400-500° C.                                                                      nickel screen 34 ± 3                                      F124   510-570° C.                                                                      Inconel ® screen                                                                        41 ± 3                                      F124   520-580° C.                                                                      shot coke     37 ± 1                                      ______________________________________                                         .sup.1 F114.sub.a = CF.sub.3 CCl.sub.2 F                                      .sup.2 F114.sub.x = Du Pont commercial CClF.sub.2 CClF.sub.2 containing       some CF.sub.3 CCl.sub.2 F                                                     .sup.3 Fl24 = CF.sub.3 CHClF                                             

The products of the reaction can be separated and purified byconventional means. The products can be used as solvents, blowingagents, refrigerants and propellants.

Practice of the invention will become further apparent from thefollowing non-limiting examples. In the following Examples the followinggeneral procedure was employed, unless otherwise indicated.

General Procedure

A flow reactor under microprocessor control was used. The reactor,unless otherwise indicated, was a 15"×1/4" o.d. or 3/8"o.d. Inconel® 600nickel alloy tube or a 15"×3/8" Hastelloy® C276 nickel alloy tube bentinto a U shape and immersed in a heated fluidized sand bath fortemperature control. Inconel® 600 is a commercial alloy containing 76%nickel, 15.5% chromium and 8% iron. Hastelloy® C-276 is a commercialalloy containing 59% nickel, 15.5% chromium, 16% molybdenum and3.75%.tungsten.

The reactor was used either empty or filled with various packingmaterials as described in the Examples. Hydrogen gas was metered intothe system through mass flow controllers. Liquid halocarbons were fedfrom a syringe pump and vaporized before entering the reactor.Conversions and yields were measured by taking gas stream samples into agas chromatograph. Product identification was by gc retention times withconfirmation by gc-mass spectrometer analysis of samples.

EXAMPLE 1 CF₃ CCl₂ F+H₂ →CF₃ CHClF+CF₃ CH₂ F

2,2-Dichloro-1,1,1,2-tetrafluoroethane (1.47 g/hr) and hydrogen (molarratio of H₂ /CF₃ CCl₂ F =1.9) were fed into the 1/4" empty Inconel®nickel alloy reactor for 38 hours at 450°-550° C. and 250 psig. A sampletaken after 14 hours at 550° C. showed an 89% conversion of CF₃ CCl₂ Fwith a 65% selectivity to CF₃ CHClF and a 32% selectivity to CF₃ CH₂ F.Overall selectivity to the two products was 97%.

EXAMPLE 2 CF₃ CCl₂ F+H₂ →CF₃ CHClF+CF₃ CH₂ F

2,2-Dichloro-1,1,1,2-tetrafluoroethane (1.47 g/hr) and hydrogen (molarratio of H₂ /CF₃ CCl₂ F =1.9) were fed into the 1/4" empty Inconel®nickel alloy reactor for 132 hours at 350°-550° C. and 250 psig. At 350°C. a 2.3% conversion of CF₃ CCl₂ F with a 76% selectivity to CF₃ CHClFand CF₃ CH₂ F was observed. A sample taken after 20 hours at 500° C.showed an 83% conversion of CF₃ CCl₂ F with a 98% selectivity to CF₃CHClF and CF₃ CH₂ F.

EXAMPLE 3

CF₃ CHClF+H₂ →CF₃ CH₂ F

2-Chloro-1,1,1,2-tetrafluoroethane (1.0 g/hr) and hydrogen (molar ratioof H₂ /CF₃ CCl₂ F=4.9) were fed into the 1/4" empty Inconel® nickelalloy reactor for 7 hours at 550° C. and 250 psig with average CF₃ CHClFconversions of 86% with 98% selectivity to CF₃ CH₂ F and 0.4%selectivity to CF₃ CH₃.

EXAMPLE 4 CF₂ C₁₂ +H₂ →CF₂ HCl

Dichlorodifluoromethane (9.0 g/hr) and hydrogen (molar ratio of H₂ /CF₂Cl₂ =1.0) were fed into the 1/4" empty Inconel® nickel alloy reactor asdescribed above for 89 hours at 300 psig, including 79 hours at500°-550° C. For 12 hours at 500° C. during this run, at a mean age of64 synthesis hours, the average conversion of CF₂ Cl₂ was 26%.

EXAMPLE 5 CF₃ CClFCF₃ +H₂ →CF₃ CHFCF₃

2-Chloroheptafluoropropane (1.5 g/hr) and hydrogen (22 cc/min) were fedinto the 1/4" empty Inconel® nickel alloy reactor for 3 hours at 450° C.and 250 psig with 30-40% conversion and a 98% selectivity to CF₃ CHFCF₃.

EXAMPLE 6 CF₃ CClFCF₃ +H₂ →CF₃ CHFCF₃

2-Chloroheptafluoropropane (1.38 g/hr) and hydrogen (22 cc/min) were fedinto the 1/4" Inconel® nickel alloy reactor filled with Inconel® nickelalloy chips (10 g). Operation at 500° C. and 250 psig for 33.3 hoursgave an average of 91.3% conversion with 99.4% selectivity to CF₃CHFCF₃.

EXAMPLE 7 CF₃ CCl₂ F+H₂ →CF₃ CHClF+CF₃ CH₂ F

2,2-Dichloro-1,1,1,2-tetrafluoroethane (2.9 or 5.9 g/hr) and hydrogen(molar ratio of H₂ /CF₃ CCl₂ F=2.2 or 4.3) were fed into the 3/8"Inconel® nickel alloy reactor filled with Inconel® nickel alloy wool(7.96 g) for 106 hours at 400°-500° C. and 250 psig. The averageconversion of CF₃ CCl₂ F over the whole period was 99.9%. For a 12-hourperiod at 450° C. with a CF₃ CCl₂ F feed rate of 5.9 g/hr (molar ratioH₂ /CF₃ CCl₂ F=4.3) the following average selectivities were observed:69% CF₃ CHClF and 26% CF₃ CH₂ F.

EXAMPLE 8 CF₃ CHClF+H₂ →CF₃ CH₂ F

2-Chloro-1,1,1,2-tetrafluoroethane (5.5 g/hr) and hydrogen (molar ratioof H₂ /CF₃ CHClF=1.1) were fed into the 3/8" Inconel® nickel alloyreactor filled with a pure nickel screen (8.77 g), operated at variousfeed rates and a pressure of 300 psig. With a CF₃ CHClF feed rate of5.48 g/hr and hydrogen (molar ratio of H₂ /CF₃ CHClF=1.1) conversion at525° C. and an average synthesis time of 82 hours averaged 47% with 98%selectivity to CF₃ CH₂ F for 12 hours. At an average synthesis time of644 hours conversion averaged 39% with 97% selectivity to CF₃ CH₂ F. At1181 synthesis hours the operating pressure was increased to 500 psig.Conversion of CF₃ CHClF averaged 68% for 14 hours with a selectivity toCF₃ CH₂ F of 98%.

EXAMPLE 9 CF₃ CHClF+H₂ →CF₃ CH₂ F

2-Chloro-1,1,1,2-tetrafluoroethane (2.7 or 5.5 g/hr) and hydrogen (molarratio of H₂ /CF₃ CHClF=1.9) were fed into the 3/8" Inconel® nickel alloyreactor filled with Inconel® nickel alloy wool (7.96 g) for 23 hours at400°-500° C. and 250 psig. Between 18 and 23 hours, at 400° C. with aCF₃ CHClF feed rate of 2.7 g/hr, the average conversion was 23% and theselectivity to CF₃ CH₂ F was 82%.

EXAMPLE 10 CF₂ Cl₂ +H₂ →CF₂ HCl

Dichlorodifluoromethane (4.5 or 33.0 g/hr) and hydrogen (molar ratio ofH₂ /CF₂ Cl₂ =1 or 0.5) were fed into the 3/8" Inconel® nickel alloyreactor filled with pure nickel screen (17.5 g) for 135 hours at 300psig. For 12 hours at 450° during this run, at a mean synthesis time of78 hours, with a CF₂ Cl₂ feed rate of 4.5 g/hr (molar ratio H₂ /CF₂ Cl₂=1.0), the average conversion of CF₂ Cl₂ was 34%.

EXAMPLE 11 CF₃ CClF₂ +H₂ →CF₃ CHF₂

Chloropentafluoroethane vapor (6 cc/min) and hydrogen (5 cc/min) werefed into a Hastelloy® nickel alloy reactor (6"×1/2" O.D.) filled withpure nickel screen (39.68 g) at 550° C. and atmospheric pressure. Thereaction products were analyzed with the following results: 59%conversion of CF₃ CClF₂ with a 97% selectivity to CF₃ CHF₂.

EXAMPLE 12 CF₃ CClF₂ +H₂ →CF₃ CHF₂

Chloropentafluoroethane vapor (5 cc/min) and hydrogen (6 cc/min) werefed into an Inconel® nickel alloy reactor (6"×1/2" O.D.) filled withpure nickel screen (51.98 g) at 550° C. and atmospheric pressure. Thereaction products were analyzed with the following results: 65%conversion of CF₃ CClF₂ with a 95% selectivity to CF₃ CHF₂.

The reaction was run under the same conditions as described above,except that the feed rates were changed to CF₃ CClF₂ (5 cc/min) and H₂(12 cc/min). The reaction products were analyzed with the followingresults: 62% conversion of CF₃ CClF₂ with an 86% selectivity to CF₃CHF₂.

EXAMPLE 13 CClF₂ CClF₂ /CF₃ CCl₂ F+H₂ →CHF₂ CClF₂ /CF₃ CHClF+CHF₂ CHF₂/CF₃ CH₂ F

A vapor mixture of CClF₂ CClF₂ (9)/CF₃ CCl₂ F(1) (5 cc/min) and hydrogen(6 cc/min) was fed into a Hastelloy® nickel alloy reactor (6"×1/2" O.D.)filled with pure nickel screen (39.68 g) at 550° C. and atmosphericpressure. The reaction products were analyzed with the followingresults: 61% conversion of CClF₂ CClF₂ /CF₃ CCl₂ F with a 46%selectivity to CHF₂ CClF₂ /CF₃ CHClF and a 34% selectivity to CHF₂ CHF₂/CF₃ CH₂ F.

EXAMPLE 14 CF₃ CCl₂ F+H₂ →CF₃ CHClF+CF₃ CH₂ F

2,2-Dichlorotetrafluoroethane vapor (5 cc/min) and hydrogen (6 cc/min)were fed into an Inconel® nickel alloy reactor (6"×1/2" O.D.) filledwith pure nickel screen (51.98 g) at 550° C. and atmospheric pressure.The reaction products were analyzed with the following results: 83%conversion of CF₃ CCl₂ F with a 5% selectivity to CF₃ CHClF and a 66%selectivity to CF₃ CH₂ F.

EXAMPLE 15 CF₃ CHClF+H₂ →CF₃ CH₂ F

2-Chloro-1,1,1,2-tetrafluoroethane vapor (5 cc/min) and hydrogen (6cc/min) were fed into an Inconel® nickel alloy reactor (6"×1/2" O.D.)filled with pure nickel screen (51.98 g) at 550° C. and atmosphericpressure. The reaction products were analyzed with the followingresults: 58% conversion of CF₃ CHClF with an 85% selectivity to CF₃ CH₂F.

EXAMPLE 16 CClF₂ CCl₂ F+H₂ →CHClFCClF₂ +CHClFCHF₂

1,1,2-Trichloro-1,2,2-trifluoroethane (3.13 g/hr) and hydrogen (molarratio=4.75) were fed into the 3/8" Inconel® nickel alloy U-tube reactoras described in the general procedure, with the exit leg filled withpure nickel screen (8 g), at 450° C. and 500 psig. Over a 6-hour periodthe reaction products were analyzed with the following results: 81%conversion of CCl₂ FCClF₂ with 96% combined selectivity to C₂ H₃ F₃, C₂H₂ ClF₃, and C₂ HCl₂ F₃. Selectivity to CClF═CF₂ was 2%. When thetemperature was raised to 475° C. for 7 hours, the average conversion ofCCl₂ FCClF₂ was 97% with 95% combined selectivity to C₂ H₃ F₃, C₂ H₂ClF₃, and C₂ HCl₂ F₃. Selectivity to CClF═CF₂ was 1%.

EXAMPLE 17 CF₃ CHClF+H₂ →CF₃ CH₂ F

2-Chloro-1,1,1,2-tetrafluoroethane (2.7 g/hr) and hydrogen (molar ratioof H₂ /CF₃ CHClF=0.2) were fed into an empty 6"×1/2" O.D. Hastelloy®C276 nickel alloy reactor for 8 hours at 535° C. and 300 psig. Theaverage conversion of CF₃ CHClF was 22% with an average 97% CF₃ CH₂ Fselectivity.

EXAMPLE 18 CF₃ CHClF+H₂ →CF₃ CH₂ F

2-Chloro-1,1,1,2-tetrafluoroethane (2.7 g/hr) and hydrogen (molar ratioof H₂ /CF₃ CHClF=1.5) were fed into 6"×1/2" O.D. Hastelloy® C276 nickelalloy reactor containing 14/20 mesh acid-washed SiC (6.5 g) for 60 hoursat 535° C. and 300 psig. The average conversion of CF₃ CHClF was 75%with an average 97% CF₃ CH₂ F selectivity.

EXAMPLE 19 CF₃ CHClF+H₂ →CF₃ CH₂ F

2-Chloro-1,1,1,2-tetrafluoroethane and hydrogen were fed at variousrates over 113 hours into the 3/8" Hastelloy® C276 nickel alloy tubeoperated at 300 psig and containing Conoco Shot coke (9.2 grams, 10 cc),a highly fused petroleum coke with a surface area of 0.5 sq m/g. For an8-hour period at 560° C. and an average time in synthesis of 102 hours,with a CF₃ CHClF feed rate of 11.0 g/hr and a hydrogen feed rate of 32cc/min (molar ratio of H₂ /CF₃ CHClF=1) the average conversion of CF₃CHClF was 13% with an average selectivity to CF₃ CH₂ F of 99%.

EXAMPLE 20 CClF₂ CClF₂ +H₂ →CHF₂ CClF₂ +CHF₂ CHF₂

Commercial 1,2-dichloro-1,1,2,2-tetrafluoroethane, containing 9% (molar)1,1-dichloro-1,2,2,2-tetrafluoroethane, and hydrogen were fed at variousrates over 150 hours into the 3/8" Inconel® nickel alloy tube operatedat 300 psig and containing Conoco Shot coke (9.2 grams, 10 cc), a highlyfused petroleum coke with a surface area of 0.5 sq. m/g. For a 16-hourperiod at 550° C. and an average time in synthesis of 59 hours, with aCClF₂ CClF₂ feed rate of 5.9 g/hr and a hydrogen feed rate of 28 cc/min(molar ratio of H₂ /CClF₂ CClF₂ =2) the average conversion of the C₂ Cl₂F₄ isomers was 84% with an average selectivity to CHF₂ CClF₂ and itsisomer of 49%, and an average selectivity to CHF₂ CHF₂ and its isomer of47%.

EXAMPLE 21 CF₃ CCl₂ F+H₂ →CF₃ CHClF+CF₃ CH₂ F

2,2-Dichloro-1,1,1,2-tetrafluoroethane (2 mL/h), which was vaporizedbefore being mixed with hydrogen (13 cc/min), was fed into a Hastelloy®C nickel alloy reactor (6"×1/2" O.D.) as described above, containingConoco Shot coke (14.0 grams, 10 mesh), a highly fused petroleum cokewith a surface area of 0.5 sq m/g at 550° C. and 100 psig. After 28hours of operation, product analysis indicated that CF₃ CCl₂ Fconversion was quantitative and selectivity to CF₃ CHClF and CF₃ CH₂ Fwas 64.7% and 33.3% respectively.

EXAMPLE 22 CF₃ CClF₂ +H₂ →CF₃ CHF₂

Chloropentafluoroethane vapor (10 cc/min) and hydrogen (10 cc/min) werefed into a Hastelloy® C nickel alloy reactor (6"×1/2" O.D.) as describedabove, charged with Conoco Shot coke (14.0 grams, 10 mesh), a highlyfused petroleum coke with a surface area of 0.5 sq m/g at 550° C. After10 hours of operation, product analysis indicated that CF₃ CClF₂conversion was 7.5% and selectivity to CF₃ CHF₂ was 94.7%.

This experiment was substantially repeated except that the CF₃ CClF₂flow was 5 cc/min and the hydrogen flow was 6 cc/min. Product analysisindicated that CF₃ CClF₂ conversion was 13.3% and selectivity to CF₃CHF₂ was 89.6%.

EXAMPLE 23

CClF₂ CClF₂ +H₂ →CHF₂ CClF₂ +CHF₂ CHF₂

Commercial 1,2-dichloro-1,1,2,2-tetrafluoroethane, containing 9% (molar)1,1-dichloro-1,2,2,2-tetrafluoroethane, and hydrogen were fed at variousrates for 172 hours into an empty 15"×3/8" O.D. Hastelloy® C276 nickelalloy tube, as described above, operated at 500 psig. For a 13 hourperiod at 500° C. and an average time in synthesis of 66 hours, with aCClF₂ CClF₂ feed rate of 5.9 g/hr and hydrogen feed rate of 10 cc/min(molar ratio of H₂ /CClF₂ CClF₂ =0.7) the average conversion of C₂ Cl₂F₄ isomers was 58% with an average selectivity to CHF₂ CClF₂ and itsisomer of 75% and an average selectivity to CHF₂ CHF₂ and its isomer of24%. For a 9 hour period at 500° C. and an average time in synthesis of148 hours, with a CClF₂ CClF₂ feed rate of 1.47 g/hr and a molar feedratio of H₂ /CClF₂ CClF₂ of 1.5 the average conversion of C₂ Cl₂ F₄isomers was 88% with an average selectivity of CHF₂ CClF₂ and its isomerof 45% and an average selectivity to CHF₂ CHF₂ and its isomer of 54%.

EXAMPLE 24 CClF₂ CCIF₂ +H₂ →CHF₂ CClF₂ +CHF₂ CHF₂

Commercial 1,2-dichloro-1,1,2,2-tetrafluoroethane, containing 9% (molar)1,1-dichloro-1,2,2,2-tetrafluoroethane, and hydrogen were fed at variousrates for 192 hours into a 15"×3/8" O.D. Inconel® 600 nickel alloy tube,as described above, containing 8.0 g of 24×100 mesh nickel screen andoperated at 500 psig. For a 10 hour period at 400° C. and a CClF₂ CClF₂feed rate of 0.7 g/hr and hydrogen feed rate of 1.7 cc/min (molar ratioof H₂ /CClF₂ CClF₂ =1); the average conversion of C₂ Cl₂ F4 isomers was61% with an average selectivity to CHF₂ CClF₂ and its isomer of 77.0%and an average selectivity to CHF₂ CHF₂ and its isomer of 22.7%.

EXAMPLE 25 CF₃ CCl₂ F+H₂ →CF₃ CHClF+CF₃ CH₂ F

2,2-Dichloro-1,1,1,2-tetrafluoroethane and hydrogen were fed at variousrates for 68 hours to an empty Hastelloy® C276 nickel alloy tube, asdescribed above, operated at 500 psig. For a five hour period at 500° C.and an average time in synthesis of 41 hours, with a CF₃ CCl₂ F feedrate of 5.9 g/hr and a hydrogen rate of 14 cc/min (molar ratio of H₂/CF₃ CCl₂ F=1), the average conversion was 64% with an averageselectivity to CF₃ CHClF of 83.6 and an average selectivity of CF₃ CH₂ Fof 15.6%.

EXAMPLE 26 CClF₂ CClF₂ +H₂ →CHF₂ CClF₂ +CHF₂ CHF₂ Chrome-Plated Reactor

Commercial 1,2-dichloro-1,1,2,2 tetrafluoroethane, containing 9% (molar)1,1-dichloro-1,2,2,2-tetrafluoroethane, and hydrogen were fed at variousrates over 55 hours into a 15"×1/4" o.d. empty chrome-plated U-tubereactor, as described above, operated at 300 psig. For a 20-hour periodat 500° C. and an average time in synthesis of 16 hours, with a CClF₂CClF₂ feed rate of 2.9 g/hr and a hydrogen feed rate of 13.3 cc/min(molar ratio H₂ /CClF₂ CClF₂ =2); the average conversion of the CClF₂CClF₂ isomers was 56% with an average selectivity to CHF₂ CClF₂ and itsisomer of 21%, and an average selectivity to CHF₂ CHF₂ and its isomer of76%.

EXAMPLE 27 CClF₂ CClF₂ +H₂ →CHF₂ CClF₂ +CHF₂ CHF₂ Aluminum Reactor

Commercial 1,2-dichloro-1,1,2,2-tetrafluoroethane, containing 9% (molar)1,1-dichloro-2,2,2,2 tetrafluoroethane, and hydrogen were fed at variousrates over 31 hours into an empty 15"×1/4" o.d. aluminum U-tube reactor,as described above, operated at 50 psig. For a 3-hour period at 500° C.and an average time in synthesis of 28 hours, with a CClF₂ CClF₂ feedrate of 1.47 g/hr and a hydrogen feed rate of 7.0 cc/min (molar ratio H₂/CClF₂ CClF₂ =2); the average conversion of the CClF₂ CClF₂ isomers was5% with an average selectivity to CHF₂ CClF₂ and its isomer of 49%, andan average selectivity to CHF₂ CHF₂ and its isomers of 33%.

EXAMPLE 28 CClF₂ CClF₂ +H₂ →CHF₂ CClF₂ +CHF₂ CHF₂ Titanium Reactor

Commercial 1,2-dichloro-1,1,2,2 tetrafluoroethane, containing 9% (molar)1,1-dichloro-1,2,2,2-tetrafluoroethane, and hydrogen were fed at variousrates over 42 hours into a 15"×1/4" o.d. empty titanium U-tube reactor,as described above, operated at 50 psig. For a 17-hour period at 500° C.and an average time in synthesis of 9.5 hours, with a CClF₂ CClF₂ feedrate of 2.9 g/hr and a hydrogen feed rate of 13.9 cc/min (molar ratio H₂/CClF₂ CClF₂ =2) the average conversion of the CClF₂ CClF₂ isomers was14.2% with an average selectivity to CHF₂ CClF₂ and its isomer of 57%,and an average selectivity to CHF₂ CHF₂ and its isomer of 24.4%.

EXAMPLE 29 CF₃ CHClF+H₂ →CF₃ CH₂ F Silicon Carbide Reactor

2-Chloro-1,1,1,2 tetrafluoroethane and hydrogen were fed at variousrates over 47 hours into a 15"×1/4" o.d. empty silicon carbide straighttube reactor, as described above, operated at 0 psig. For a 12-hourperiod at 600° C. and an average time in synthesis of 29 hours, with aCF₃ CHClF feed rate of 2.74 g/hr and a hydrogen feed rate of 8.2 cc/min(molar ratio H₂ /CF₃ CHClF=1); the average conversion of the CF₃ CHClFwas 4.3%, with an average selectivity to CF₃ CH₂ F of 89.7%.

EXAMPLE 30 CF₃ CCl₂ F+H₂ →CF₃ CHClF+CF₃ CH₂ F Silicon Carbide Reactor

2,2-Dichloro-1,1,1,2-tetrafluoroethane 2.94 g/hr were fed into a siliconcarbide straight tube reactor, as described above, with 6.4 cc/min ofhydrogen (molar ratio H₂ /CF₃ CCl₂ F=1) operated at 0 psig for 41 hours.Over a 15-hour period at 500° C. and an average time in synthesis of 27hours; the average conversion of CF₃ CCl₂ F was 23% with an averageselectivity to CF₃ CHClF of 54% and an average selectivity to CF₃ CH₂ Fof 0.6%.

EXAMPLE 31 CClF₂ CClF ₂ +H₂ →CHF₂ CClF₂ +CHF₂ CHF₂ Silicon CarbideReactor

Commercial 1,2-dichloro-1,1,2,2 tetrafluoroethane, containing 9% (molar)1,1-dichloro-1,2,2,2 tetrafluoroethane, and hydrogen were fed at variousfeed rates over 38 hours into a straight tube silicon carbide reactortube, as described above, operated at 0 psig. For a 12-hour period at575° C. and at an average time in synthesis of 14 hours, with a feedrate of 13.9 cc/min of hydrogen and 2 grams/hr of CClF₂ CClF₂ (molarratio H₂ /CClF₂ CClF₂ =2); the average conversion of the CClF₂ CClF₂isomers was 35.6% with an average selectivity to CHF₂ CClF₂ and itsisomers of 28% and an average selectivity to CHF₂ CHF₂ and its isomersof 27%.

EXAMPLE 32 CF₂ Cl₂ +H₂ →CF₂ HCl+CH₂ F₂ Silicon Carbide Reactor

Dichlorodifluoromethane (2.6 g/hr) and hydrogen (molar ratio H₂ /CF₂ Cl₂=1.0) were fed into an empty 1/2"×15" silicon carbide straight tubereactor, as described above, over a 28-hour period. For four hours at575° C. during this run, at an average synthesis time of 26 hours; theaverage conversion of CF₂ Cl₂ was 35.6%.

EXAMPLE 33 CF₃ CCl₃ +H₂ →CF₃ CHCl₂ +CF₃ CH₂ Cl Hastelloy® Nickel AlloyReactor

1,1,1-Trichloro-2,2,2-trifluoroethane and hydrogen were fed into anempty 15"×3/8" Hastelloy® C276 nickel alloy U-tube reactor, as describedabove, at 300 psig for a period of 28 hours. Over a 6-hour period at425° C. and 300 psig, at an average time in synthesis of 17 hours, witha feed rate of CF₃ CCl₃ of 6.25 g/hr and a hydrogen feed rate of 14.0sccm (molar ratio H₂ /CF₃ CCl₃ =1.0); the average conversion of CF₃ CCl₃was 33% with a selectivity to CF₃ CHCl₂ of 95% and a selectivity to CF₃CH₂ Cl of 5%.

EXAMPLE 34 CCl₄ +H₂ →CHCl₃ +CH₂ Cl₂ Inconel® Nickel Alloy Reactor

Carbon tetrachloride (6.57 g/hr) and hydrogen (200 sccm) were fed intoan empty 15"×1/4" Inconel®600 nickel alloy U-tube reactor, as describedabove, operated at pressures between 0 psig and 300 psig for 149 hours.For a 10-hour period at 457° C. and 300 psig and an average time insynthesis of 136 hours, with a CCl₄ feed rate of 6.57 g/hr and ahydrogen feed rate of 200 sccm (molar ratio H₂ /CCl₄ =12); the averageconversion of CCl₄ was 45% with an average selectivity to CHCl₃ of 59%and an average selectivity to CH₂ Cl₂ of 2.8%.

EXAMPLE 35 CF₃ CHClF+H₂ →CF₃ CH₂ F High Hydrogen Ratio

2-Chloro-1,1,1,2-tetrafluoroethane and hydrogen were fed at varyingrates for over 48 hours to a 56" ×1/4" Inconel® 600 nickel alloy coilreactor at 300 psig and temperatures between 550° and 600° C. For 4hours at 600° C. at an average time in synthesis of 39 hours, with a CF₃CHClF feed rate of 1.6 mL/hr and a H₂ feed rate of 130 sccm (H₂ /CF₃CHClF mol ratio=20) the average conversion of CF₃ CHClF was 83% and theselectivity to CF₃ CH₂ F was 94%. At a lower H₂ flow of 65 sccm and thesame CF₃ CHClF feed rate and temperature (H₂ /CF₃ CHClF mol ratio=10)the average conversion of CF₃ CHClF over a 5-hour period was 90% with a94% selectivity to CF₃ CH₂ F.

EXAMPLE 36 CF₃ CHClF+H₂ →CF₃ CH₂ F High Hydrogen Ratio

2-Chloro-1,1,1,2-tetrafluoroethane and hydrogen were fed at variousrates for 1207 hours into a 15"×3/8" Inconel® 600 nickel alloy U-tube,packed with 8.77 g 150 mesh nickel screen, and operated at varioustemperatures at 300 psig. For a 23-hour period at 550° C. and an averagetime in synthesis of 755 hours with a CF₃ CHClF feed rate of 0.4 ml/hourand a hydrogen feed rate of 18 sccm/min (molar ratio H₂ /CF₃ CHClF=11),the average conversion of CF₃ CHCl was 99.6% with a selectivity to CF₃CH₂ F of 93%.

EXAMPLE 37 CCl₂ FCF₃ +H₂ →CHClFCF₃ +CH₂ FCF₃ High Hydrogen Ratio

1,1-Dichloro-1,2,2,2-tetrafluoroethane and hydrogen were fed at variousrates for 237 hours into a 15"×3/8" Hastelloy® C nickel alloy U-tubepacked with 9.29 g of Conoco shot coke and operated at varioustemperatures at 300 psig. For a 5-hour period at 575° C. and an averagetime in synthesis of 227 hours with a CCl₂ FCF₃ feed rate of 36 mL/hrand a hydrogen feed rate of 50 sccm/min (molar ratio H₂ /CCl₂ FCF₃ =40),the average conversion of CCl₂ FCF₃ was 100%. The selectivity toCHClFCF₃ was 32% and the selectivity to CH₂ FCF₃ was 59%.

EXAMPLE 38 CF₃ CClF₂ +H₂ →CF₃ CHF₂

2-Chloro-1,1,1,2,2-pentafluoroethane and hydrogen were fed at variousrates to 15"×3/8" Hastelloy® C276 nickel alloy U-tube operated at 300psig and various temperatures for 136 hours. For 10 hours, at an averagetime in synthesis of 58 hours and a temperature of 575° C., with a CF₃CClF₂ feed rate of 2.1 g/hr and a hydrogen feed rate of 14.0 sccm (molarratio H₂ /CF₃ CClF₂ =2.5), the conversion of CF₃ CClF₂ was 89.5% and theselectivity to CF₃ CHF₂ was 99.9%.

For an 8-hour period at an average time in synthesis of 131 hours and atemperature of 575° C., with a feed rate of CF₃ CClF₂ of 4.15 g/hr and ahydrogen feed rate of 329 sccm (molar ratio H₂ /CF₃ CClF₂ =30), theaverage conversion of CF₃ CClF₂ was 39% with a selectivity to CF₃ CHF₂was 99.6%.

Particular embodiments of the invention are included in the examples.Other embodiments will become apparent to those skilled in the art froma consideration of the specification or practice of the inventiondisclosed herein. It is understood that modifications and variations maybe practiced without departing from the spirit and scope of the novelconcepts of this invention. It is further understood that the inventionis not confined to the particular formulations and examples hereinillustrated, but it embraces such modified forms thereof as come withinthe scope of the following claims.

What is claimed is:
 1. A process for the hydrogenolysis of a halocarbonstarting compound of the formula C_(n) H_(m) F_(p) X_(q), wherein X isCl or Br, n is 2 to 10, m is 0 to 20, p is 0 to 21, and q is 1 to 22,provided that m+p+q equals 2n+2 when the compound is acyclic and equals2n when the compound is cyclic, comprising:contacting said halocarbonstarting compound with at least 0.1 mole of hydrogen per mole of saidhalocarbon starting compound in an empty reaction vessel of nickel toits alloys at a pressure within the range of from 0 psig to 1000 psig,at a temperature within the range of from 350° C. to 700° C. and for atime sufficient to produce a saturated product wherein at least one Xhas been replaced by hydrogen.
 2. The process of claim 1 wherein thetemperature ranges from 400° C. to 700° C. and the pressure is 0 to 500psig.
 3. The process of claim 1 wherein X is Cl; n is 2 to 4, m is 0 to8, p is 0 to 9 and q is 1 to
 9. 4. The process of claim 2 wherein thehalocarbon starting compound is selected from the group CF₃ CCl₃ and CF₃CClF₂ ; and wherein at least 90% of the product of said hydrogenolysiscontains the same number of fluorine substituents as said halocarbonstarting compound.
 5. The process of claim 1 wherein the halocarbonstarting compound is selected from the group consisting of CF₃ CCl₂ F,CF₃ CHClF, CF₃ CClFCF₃, CClF₂ CClF₂, CF₃ CCl₃ and CF₃ CClF₂ ; andwherein less than 10% olefinic by-product is produced.
 6. The process ofclaim 5 wherein CCl₂ FCClF₂ is reacted with hydrogen and C₂ ClF₃by-product is produced.
 7. The process of claim 5 wherein CClF₂ CClF₂ isreacted with hydrogen and C₂ F₄ by-product is produced.
 8. The processof claim 1 wherein the halocarbon starting compound is selected from thegroup consisting of CF₃ CCl₂ F, CF₃ CHClF, CF₃ CClFCF₃, CClF₂ CClF₂, CF₃CCl₃ and CF₃ CClF₂ ; and wherein less than 10% coupled by-product isproduced.
 9. The process of claim 8 wherein CClF₂ CClF₂ is thehalocarbon starting material.
 10. The process of claim 8 wherein CClF₂CClF₂ is reacted with hydrogen and CF₃ CF═CFCF₃ by-product is produced.11. The process of claim 1 wherein n is 3 and wherein the hydrogenolysisproduct contains from 1 to 4 hydrogen substituents.
 12. The process ofclaim 1 wherein the halocarbon starting compound is selected from thegroup consisting of CF₃ CCl₂ F, CF₃ CHClF, CF₃ CClFCF₃, CClF₂ CClF₂, CF₃CCl₃ and CF₃ CClF₂ ; and wherein less than 10% of hydrocarbons areproduced.
 13. A process for the hydrogenolysis of a halocarbon startingcompound of the formula C_(n) H_(m) F_(p) Cl_(q), wherein n is 2 to 4, mis 0 to 8, p is 0 to 9, and q is 1 to 9, provided that m+p+q equals 2n+2when the compound is acyclic and equals 2n when the compound is cyclic,comprising:contacting said halocarbon starting compound with at least0.1 mole of hydrogen per mole of said halocarbon starting compound in anempty reaction vessel of nickel or its alloys at a pressure, atemperature and a time sufficient to produce a saturated product whereinat least one chlorine has been replaced by hydrogen at an activationenergy of about 47 Kcal/mole or more, at least 90% of the product ofsaid hydrogenolysis being a saturated product containing the same numberof fluorine substituents as the halocarbon starting compound.
 14. Theprocess of claim 13 wherein the halocarbon starting material is selectedfrom the group consisting of CClF₂ CClF₂, CCl₂ FCF₃ and CHClFCF₃.
 15. Aprocess for the hydrogenolysis of a halocarbon starting compound of theformula C_(n) H_(m) F_(p) X_(q), wherein X is Cl or Br, n is 2 to 4, mis 0 to 8, p is 0 to 9, and q is 1 to 9, provided that m+p+q equals 2n+2when the compound is acyclic and equals 2n when the compound is cyclic,comprising:contacting said halocarbon starting compound with at least0.1 mole of hydrogen per mole of said halocarbon starting compound in areaction vessel of nickel or its alloys which is packed with formedshapes of aluminum, molybdenum, nickel, cobalt, or their alloys, at apressure within the range of from 0 psig to 1000 psig, at a temperaturewithin the range of from 500 C. to 700 C. and for a time sufficient toproduce a product wherein at least one X has been replaced by hydrogen;at least 90% of the product of said hydrogenolysis being a saturatedproduct containing the same number of fluorine substituents as thehalocarbon starting material.
 16. The process of claim 15 wherein saidpacking is in the form of perforated plates, saddles or rings.
 17. Theprocess of claim 16 wherein said packing is in the form of perforatedplates.
 18. The process of claim 16 wherein the packing is of nickel ora nickel alloy.
 19. The process of claim 15 wherein the halocarbonstarting compound is selected from the group consisting of CF₃ CClFCF₃,CF₃ CCl₂ F, CF₃ CHClF, CClF₂ CClF₂, CHF₂ CClF₂, C₂ F₅ Cl, CClF₂ CCl₂ F,CF₃ CCl₃, CCl₂ FCCl₂ F and CClF₂ CCl₃.
 20. The process of claim 15wherein the halocarbon starting material is selected from the groupconsisting of CClF₂ CF₃, CCl₂ FCF₃, and CCl₃ CF₃.